The type and number of image processing innovations being developed in the telecommunications and personal computer fields continue to grow rapidly. In particular, significant efforts are being made to develop advanced multi-media communication systems for use in the home. The prevailing consensus in industry is that success of these multi-media innovations will be achieved by adding processing capability to ordinary television sets. The most likely implementation of this processing capability will be to use a "set top box" that provides for interactive communications between the user and the television set and that executes a variety of software programs for processing data during the course of such exchanges. Further, the set top box will also most likely incorporate processing sub-systems able to transmit and receive audio and video data over cable television lines and/or telephone lines serving the home. Finally, the set top box may also execute more routine computer application software, such as word processing and spread sheets.
At the same time, many new technologies have been developed that incorporate multi-media and TV signal processing capabilities into standard personal computer systems. These technologies enable personal computers (PCs) to display full-motion video, audio, and music retrieved from CD-ROM, or to demodulate standard broadcast signals, such as NTSC, PAL, or SECAM signals, and display the TV picture within a window on the screen of the PC monitor.
Presently, development of both the "set top box" multi-media systems and the PC-based innovations have encountered significant problems, including the high cost and complexity of the hardware used and the fact that both technologies are somewhat redundant. Specifically, currently available PC-based systems generally require the use of costly, space-consuming video cards to process a received video signal. Further, the video frames are generally restricted to display in a window within the background (graphics) display on the PC display screen. Due to the generally small size of PC monitor screens, especially laptop PC screens, and the even smaller size of the window in which the video frames must be displayed, this method of displaying a video picture is less than desirable. Among other things, there is a substantial loss of detail in the picture and the small window sizes make viewing the TV picture difficult from anything other than a short distance.
Additionally, multi-media systems that use full-motion video images retrieved from CD-ROM are adversely effected by the bandwidth limitations of the CPU and/or the internal busses of the PC. Some multi-media systems attempt to minimize these bandwidth limitations by using compression algorithms which update or change only a part of the image at a time. Other applications attempt to overcome the bandwidth limitations by using less frames per second to form the image, which often results in a tearing in the video display.
The "set top box" approach to multi-media systems and interactive television is also limited in that current "set top box" designs generally only contain the minimum hardware necessary to perform certain application-specific tasks, such as two-way communication across telephone lines for home shopping or home banking applications. Present "set top box" proposals lack the more powerful general-purpose processing capabilities inherent in PC systems. Upgrading the capability of a "set top box" by incorporating devices such as CD-ROM drives, better CPUs and more memory, would substantially increase hardware costs. In fact, as more and more hardware is added, the "set top box" more closely resembles a personal computer than a simple control device for interactive applications and/or video games.
Therefore, a need has arisen for electronic devices and systems capable of executing multi-media applications that are low cost, require a minimum amount of hardware, and that display processed video images on large screen television sets. There is a further need for electronic devices and systems that enable small portable computers to use the large screen of a conventional television set for the display of text and data during the execution of computer applications, such as word processing and spread sheet programs.